15 Questions
Which of the following best defines functional dependency?
A set of attributes X functionally determines a set of attributes Y if the value of X determines a unique value for Y.
What does the notation X → Y represent in the context of functional dependencies?
X functionally determines Y in the relation instance.
What is the goal regarding functional dependencies?
To determine the properties of functional dependencies and find ways to manipulate them.
In what way are functional dependencies derived?
From real-world constraints on the attributes.
What does X → Y hold, as per the definition of functional dependencies?
$ ext{If } t1[X]=t2[X]$, then $t1[Y]=t2[Y]$ for any two tuples $t1$ and $t2$ in any relation instance $r(R)$.
Explain the concept of functional dependencies and provide an example to illustrate it.
Functional dependencies refer to the relationship between sets of attributes in a relation. For example, in a relation with attributes A and B, if for every unique value of A, there is only one corresponding value of B, then A functionally determines B. An example could be a relation representing employees, where the employee ID uniquely determines the employee's name.
What are the inference rules for functional dependencies and how are they applied?
The inference rules for functional dependencies are used to derive new functional dependencies from the given set of functional dependencies. These rules include augmentation, transitivity, and decomposition. For example, if X → Y and Y → Z, then by transitivity, we can infer X → Z.
How are sets of functional dependencies proved to be equivalent, and why is this important in database design?
Sets of functional dependencies are proved to be equivalent by showing that each set implies the other. This is important in database design to ensure that the set of functional dependencies chosen to enforce constraints on the data is minimal and does not contain redundant dependencies.
Explain the concept of minimal sets of functional dependencies and their significance in relational database design.
Minimal sets of functional dependencies are the smallest sets of dependencies that still hold all the constraints of the given set of dependencies. They are significant in relational database design as they help in reducing redundancy and anomalies in the database, leading to a more efficient and normalized database design.
How can functional dependencies be displayed graphically on a relation schema, and why is this visualization useful in database design?
Functional dependencies can be displayed graphically on a relation schema by using arrows to represent the dependencies between attributes. This visualization is useful in database design as it provides a clear understanding of the dependencies and constraints within the database, aiding in the normalization and optimization of the database schema.
Functional dependencies are derived from the real-world ______ on the attributes in a database. They specify a constraint on all relation instances and can be displayed graphically on a relation schema as in Figures in Chapter 14. FDs are derived from the real-world ______ on the attributes Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 15- 4 1.
constraints
Functional dependencies are derived from the real-world ______ on the attributes in a database. They specify a constraint on all relation instances and can be displayed graphically on a relation schema as in Figures in Chapter 14. FDs are derived from the real-world constraints on the attributes Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 15- 4 1.
constraints
For any two tuples t1 and t2 in any relation instance r(R): If t1[X]=t2[X], then t1[Y]=t2[Y] X → Y in R specifies a ______ on all relation instances r(R) Written as X → Y; can be displayed graphically on a relation schema as in Figures in Chapter 14. ( denoted by the arrow: ).
constraint
For any two tuples t1 and t2 in any relation instance r(R): If t1[X]=t2[X], then t1[Y]=t2[Y] X → Y in R specifies a ______ on all relation instances r(R) Written as X → Y; can be displayed graphically on a relation schema as in Figures in Chapter 14. ( denoted by the arrow: ).
constraint
A set of attributes X functionally determines a set of attributes Y if the value of X determines a unique value for Y. Our goal here is to determine the properties of functional dependencies and to find out the ways of ______ them.
manipulating
Test your knowledge of relational database design algorithms by taking this quiz. Learn about further topics in functional dependencies, inference rules, equivalence of sets of FDs, and minimal sets of FDs.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
